diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 57248bccadbc..2b98a173136f 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -256,7 +256,8 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	struct dw_i2c_dev *dev;
 	u32 acpi_speed, ht = 0;
 	struct resource *mem;
-	int irq, ret;
+	int i, irq, ret;
+	const int supported_speeds[] = { 0, 100000, 400000, 1000000, 3400000 };
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
@@ -297,9 +298,16 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 	}
 
 	acpi_speed = i2c_acpi_find_bus_speed(&pdev->dev);
-	/* Some broken DSTDs use 1MiHz instead of 1MHz */
-	if (acpi_speed == 1048576)
-		acpi_speed = 1000000;
+	/*
+	 * Some DSTDs use a non standard speed, round down to the lowest
+	 * standard speed.
+	 */
+	for (i = 1; i < ARRAY_SIZE(supported_speeds); i++) {
+		if (acpi_speed < supported_speeds[i])
+			break;
+	}
+	acpi_speed = supported_speeds[i - 1];
+
 	/*
 	 * Find bus speed from the "clock-frequency" device property, ACPI
 	 * or by using fast mode if neither is set.
diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index e98e44e584a4..22ffcb73c185 100644
--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -341,8 +341,10 @@ static int ismt_process_desc(const struct ismt_desc *desc,
 			break;
 		case I2C_SMBUS_BLOCK_DATA:
 		case I2C_SMBUS_I2C_BLOCK_DATA:
-			memcpy(&data->block[1], dma_buffer, desc->rxbytes);
-			data->block[0] = desc->rxbytes;
+			if (desc->rxbytes != dma_buffer[0] + 1)
+				return -EMSGSIZE;
+
+			memcpy(data->block, dma_buffer, desc->rxbytes);
 			break;
 		}
 		return 0;